I guess I'm someone who is successful by your standards, though as always there's a good dose of imposter syndrome for me.
I have a job where I'm able to make big changes within the organisation, have between 7-15 years less experience than those in equivalent level roles, and have a salary that's in the top 20% for my household type, and I suspect higher for my age group. My role is broadly varied and satisfying, but does have tedious bits.
I do think luck plays a big part:
I was lucky to be born into a family with supportive parents who valued education and encouraged me to do well (or try hard if I didn't do well!), but balanced that with avoiding an obsession with perfection. I've of my great grandma's sayings was "only perfect is good enough" - my parents countered that with "why do a 100% job if an 80% job will do?".
I was lucky to be born bright, and only suffering from limited disabilities from my teenage years.
I was lucky to get my degree from an exceptional university (because although I was bright enough for my degree, I'm sure there were others, equally bright, who were passed over).
But, countering that, is the fact that I've worked really very hard.
I didn't think I worked hard when I did my a levels, or prepared for uni, say. But in fact I did 6 a levels, teaching myself one, did extra modules in the summer to prepare for uni, and read about 15 books ready for my uni interview.
I read papers and articles on my interviewers' specialisms. I've done the same thing for every job interview. I've now done multiple job interviews where by 5 minutes through I know the job wouldn't suit me, but because I've done my research I can see what they are going to want, so can present that persona. Since I worked out how to do this, I've got every single job I've applied for.
But again, that was more luck - a friend of a friend of a friend was very senior in recruitment at a large multinational and kindly gave me an hour of her time to talk me through how to improve my technique.
So I guess a mixture of luck (bright, useful friends etc) and taking advantage of what luck offers you (asking for work experience, for help to improve etc).